Safety blasting plug



April 1938- I J. HElTZMAN 2,115,388

SAFETY BLASTING PLUG Filed Oct. 8, 1934 2 Sheets -Sheet 1 RICHARD JHITZMflN April 1938- R. J. HEITZMAN 2,115,388

SAFETY BLASTING PLUG Filed 001:. 8 1934 2 Sheets-Sheet 2 R ICHARD (IHE/Tz MAN l atented Apr. 26, 1Si38 Q um'rsn .sm'rss PATENT SAFETYBLAST1NG. PLUG Richard J. lieitzm'am, Shamokin, Pa., assignor orone-fourth to William E. Ressler, Shamokin, Pa.

Application October 8, 1934, Serial Nat-11435 -4 Claims. '(Cl. 102-11)This invention relates to; blasting plugs and is of which the samecharacters of reference have an improvement upon the type of blastingplug been employed to denote identical parts: :described'and claimed inmy Patent No. 1,896,817. Figure 1 is a longitudinal section through a Igranted February '7 1933. The present improvebore hole showing one formof my improved ment as wellas: the blasting plug forming. the blastingplug in position with respect to the dysubject. matter of said patent isparticularly em-' namite and the sand packing; ployed in mining andquarrying and has for its Figure 2 is a perspective view of the blastinggeneral object to increase the safety factor of plug'shown in Figure 1;v e such devices by avoidingthos'e causes of misfire Figure 3 is an endelevation;

ordinarily attributable to short circuiting, and Figure 4 is aperspective view of a cylindrical 10 should a misflre occur throughinherentdefect sponge rubber blasting plug;

in the detonating cap, the invention affords a safe Figure 5 is aperspective view partly in secmeans for the extraction ofthedetonatingicap tion through a cylindrical soft rubber plug havirom thebore hole. ing a single wire slot extending throughout the '15 Thecharacteristic features of the invention length thereof; covered in thepatent aforementioned are the Figures 6 and 7 are respectively aperspective absence of metal in the construction of the blastview andend elevation of a cylindrical soft blasting plug and the provision ofan expansible anteing plug having'two wire slots; i r or portion whichunder the tamping pressure Figures Band 9 are similar views showingspreads to conform to the wall of the bore hole another form of. theinvention in which the blast- I in a firm and gas-tight manner, the rearportion 'in'g plug is of relatively hard material and. probeing of suchnature as to be readily penetrated videdwith asingle wire slot; byanauger for the purpose-of effecting the with-- Figures 10 and 11 aresimilar views showing a drawal of the plug in the event of a mis'flre."Since plug of hard rubber or its equivalent having two short circuitingis ordinarily caused by abrasion .late'ral wire slots; 25

. of one of the wires leading to the detonating cap- Figure 12 is aperspective view of a hard blastincident to the friction of tamping, theinvention ing plug having no provisions for the wires; of the patentsafeguards the wires by providing Figure 13' is an end elevation of thesame; I i a separate bores in the plug through which the Figures 14 and15 are respectively a perspec- *"3oW e p y. threaded, keeping them tiveview and end elevation of a composite plug 1 .apart from one another andaway from the wall havingthe anterior portionsoit and the posterior ofthe bore hole. a portion hard with a single wire slot extending Inpractice however'it has been found at times through the hard portiononly; and somewhat dificult to thread the wires through Figures 16 and1'7 are similar views showing the the bore holes on account orinsufficient illuminacomposite plug with the wire slot extending tion inthe mine or the ravelled nature of the through both the hard and softportions. insulation of the wire at its free ends. The pres- Referringnow in detail to the several figures ent invention thereforehas for itsspeciiicoband first adverting to that form of the invenject theprovision of lateral slots into which the tion shown in Figures 1,;2.and 3, the numeral 40 wire may be pressed and retained, on operation irepresents a plug preferably of conical form 40 which can be performedbythe sense of feeling throughout its anterior portion, and having aalone and which can bedoneif need be in the cylindrical zone 2 at itsposterior end, with an dark. a Y

intermediate taper 3. The entire plug is pref- .Another object of theinvention is to makethe erably made of a softcompressible material such'i blasting plug of such yielding material that even as sponge rubberwhich material has not only the :45 i n in the absence of 'any bore forreceiving the wires advantage of inherent softness, but also has'lmv thesame may be placed alongside the plug in -prisoned air bodies whichassist. in cushioning customary manner-as .itis inserted in the bore theimpact of the explosion. A lateral slot 6 for hole and theplug willyield to the shapeof the receiving the ignition wires is formed in the5g givireishas it is tamped into place, without abradcylindrical z'onevand opens into the tapered por- 5(1 .ng em.

tion 3. Figure 3 shows that the slot may'consist Other objects ofjltheinvention will appearas of a tubular recess opening to the exterior plugthe following. description of a number of 'em- .by amerefslitiwhich'spreads to admit the wires bodiments of the invention proceeds.and then springs back into closed position so i In thedrawingsthijoughout the several figures that the slot 4 completely encompassesthe wires 55 tendency to abrade' t the plug by means of shielding themfrom coming in contact with the wall of the bore hole. The posterior endof the cylindrical zone is preferably concaved to guide the tamping rodor ram so' as to avoid its corning in contact with the wires at'theirpoint of emergence from the plug at which point they are close togetherand special precaution must be taken to prevent the insulation becomingdam- In practice, the sticks 'of dynamite 6 having been put in place inthe bore hole with the detonating cap J embedded in the last stick and.the wires 8 and {leading therefrom to the exterior of the bore hole, thesafety plug is taken and, the two wires 8 and 9 pressed through the slit5 into theslot 4.. The blasting plug is then thrust into the bore holeand slid along. the wires under the pressure of theram or tamper untilits anterior end comes adjacent the final stick of dynamite. Furtheraction of the tamper or ram causes the soft rubber to expand radiallyfilling the bore hole and coming into intimate and sealing relation withthe wall of the bore hole. The enlarged cylindrical portion of theblasting plug forms a-tightseal against the wall of the bore holepreventing the escape of gases until the explosion has expended itsforce.

In view of the fact that the portion I is conical, it does not come intointimate contact with the wires until the blasting plug has been pushedentirely into place. Consequently, there is no e wires against the wallof the bore hole.

If a misfire occurs it is an easy matter to insert an anger, boring intothe posterior portion of the blasting plug and to draw it out withoutthe risk of sparks which might cause an explgsi on.

In Figure 4 a form of the invention is shown in which the blasting plugI0 is an. undiflferenti'ated cylinder of soft material such as spongerubber, no slots being provided for the, protection. of the wires. Thiscylinder is pushed into the. bore hole with the tamper, its-yieldingnature; causing it to conform to the wires'as it is pushed in. When itis in final position, a few blows with the tamper expand it radially'andretain it in place.- v f Figure '5' is a blasting plug ll of similarshape andmaterial, but in this instance a slot 4 ex' tendslongitudinally therethrough and opens in the lateral surface of the plugby means of they slit- 5 which closes. after the wires have been pushedin. The manner of inserting this plug is l the same as in the previouslydescribed modifi- I a cation. '1.

In those forms of the invention which have been described up to thepresent time, both wires. .3 are introduced into the same slot. "Figures-6 and 7 show a further modificatmn of theinvention' in which the wiresare independently inserted in different slots. The cylindrical plug I2is of soft material, having a pair of similar bores II and. t4 extendingtherethrough in parallel relation i and communicating with the lateralsurface or slits l5 and. I8. One of the ignition wires ispressed into,each slot just before'the plug is introduced in thebore hole. Figures8, 9, 10 and 11 are respectiv l per? spective views and views in-endelevation of two forms of plug which are a departure of those formspreviously described inasmuch as they are of hard material throughout.'I'heplug l1 shownall M m' Figure-8 is provided with a singl'eopengroove peripheral position .of

' of the ignition wires.

rialsuch as -.tion 24 soft anterior portion 21 and ignition wires.

ing into the lateral surface of said body by means of a yieldthediametrical, dimension l8 for the reception of the two ignition .wireswhereby when the plug is driven into placethe wires are protected-frombeing'abraded against the wall of the bore hole. In this form of theinvention no provision is made for sealing the 5 plug in the gas-tightmanner its sole claim to patentability being in protecting the wires. It

is also characterized by being non-metallic and the posterior end isreadily penetrable by an auger for removing the plug: On account of thew the wires there is no risk of the auger boring into the wires. v Theplug l9 shown in Figure 10 is similar to that shown in Figureexcepting'that there aretwo longitudinal grooves 20 and 2|, one for each15 Figures 12 and 13 show a hard rubber plug of and having no provisionfor safeguarding the ignition wires. It is readily removable by'means ofan auger of producing a spark;

' Figure 14 shows a composite blasting plug having the anterior portionZSformed of soft matesponge rubber and the posterior porbeing-made. ofhard material such for 245 example as hard rubber. The hard portion-hasan open groove 25 extending, therethrough, but the soft portion isdevoid of any such groove. The wires are introduced laterally into thegroove 2! be of the portion which extend from the groove II. Figure 16shows a composite plug 26 having a" portion Hi In this instance-bothportions are provided with an open slot extending longltudinallytherethrough and-adapted toreceive the While I have in the abovedescription defined 40 extending longitudinally therethrough andopenlateral surface of said plug, the posterior end of said plug beingconcave;

ing-walled narrow slit. 3. Safety blasting plug. comprising a bodyofyielding rubber having. a longitudlnal'bore ex-" tendingtherethroughcommunicating with the lateral surface of said body by means of ayield-. ing-walled slit of'such-normal width'dimension gg asto retainiufsaidborea wire forced through said'slit. a w '4. Safety blasting plugcomprising a body of yielding rubber having l a longitudinal boreextending therethrough communicating with ing walled sun said slit beingof less width than totretain in said borea wiretforccd through said ahard posterior 35

